高黏度温敏性几丁聚糖水凝胶的制备及特性初步研究

目的 改进制备工艺，提高几丁聚糖，甘油磷酸钠水凝胶（chitosan／glycerol phosphate。C／GP）的黏度，以期拓展其应用范围。方法采用改进的消毒方法，即将几丁聚糖单独进行高压蒸汽消毒，制备高黏度温敏性C／GP（highviscousC／GP,HV-C／GP）。并采用常规方法制备C／GP。Gemini流变仪动态检测HV-C／GP、C／GP流变学变化，评估黏度提高以后材料的初始黏度、胶凝温度和胶凝时间变化。将凝胶化的两种材料，放入PBS液中，于0、1、2、5、10和25d取出，干燥称重，计算失重率，比较两种材料的体外降解情况。采用扫描电镜观察两种材料的超微结构。结果脱乙酰度91％的C／GP初始黏度为1．81Pas，而HV-C／GP为17．24Pas，后者较前者提高了近10倍。C／GP的胶凝温度为37℃，HV-C／GP为34℃：在胶凝温度下，两者的胶凝时间约为5min。0．5mLHV-C／GP和C／GP凝胶化后第1天，失重率分别约为72．5％和55．4％，此后质量逐渐降低，至第25天分别为90．8％和78．2％。扫描电镜下两种材料均可以观察到多孔网络结构，C／GP孔径为50～100μm，HV-C／GP孔径为30～50μm，后者较前者明显缩小。结论通过改进消毒方法制备的HV-C／GP黏度明显提高，但温敏性变化不大；降解时间有所延长；扫描电镜观察可见多孔网络状结构，且孔径减小。

PREPARATION OF HIGH VISCOUS CHITOSAN/GLYCEROL PHOSPHATE AND PRELIMINARY STUDIES ONITS PROPERTIES

OBJECTIVE: To increase the viscosity of chitosan/glycerol phosphate (C/GP) and to improve its preparation technique in order to develop the application range of C/GP. METHODS: Chitosan was treated by high-pressure vapor sterilization in order to prepare high viscous C/GP (HV-C/GP) and prepare C/GP by standard methods. The rheologic changes of HV-C/GP and C/GP were detected dynamically by the Gemini rheometer. The initial solution viscosity, gelation temperature and gelation time were evaluated after the viscosity of the materials were increased. Two gelation materials were placed into continuous flow thermostated cells under the same condition and harvest them at predetermined time intervals, 1st, 2nd, 5th, 10th and 25th days, then they were dried, weighed and the mass loss rate was calculated. Ultrastructure of the freeze-dried samples was visualized by the scanning electron microscope. RESULTS: The initial viscosity of C/GP was 1.81 Pas and that of HV-C/GP was 17.24 Pas. The latter one increased 10 times as well as the former one. The gelation temperature of C/GP was 37 degrees C and that of HV-C/GP was 34 degrees C. There was no remarkable difference in gelation time between them. The mass loss rate of HV-C/GP at first day was 72.5% and at 25th days was 90.8%, while that of C/GP was 55.4% and 78.2%. Porous network structure was observed by the scanning electron microscope in both of them. The pore diameter of C/GP was 50-100 microm and that of HV-C/GP was 30-50 microm, which was obviously smaller than the former. CONCLUSION: The viscosity of HV-C/GP prepared by improved technique obviously increases and the thermosensitivity has no significant changes. The degradation time of HV-C/GP in vitro lengthens. The micrographs show that the HV-C/GP gels are porous and the pore diameter are smaller than C/GP.